Power cables linked to cancer

Children living near high-voltage power lines are substantially more likely to develop leukaemia, researchers from Oxford University and the national electricity grid report today in the British Medical Journal.

Those living within 200 metres of the overhead cables were 70% more likely to develop the disease than similar children living more than 600 metres away. And those living between 200 and 600 metres away had a 20% increased risk.

The results were based on an eight-year investigation into the home circumstances of the 9,700 children who developed leukaemia in England and Wales between 1962 and 1995. Since the 1950s the National Grid has erected more than 4,000 miles of high-voltage overhead lines to carry electricity, usually at 275,000 volts or more.

The researchers found 64 of the children lived at birth within 200 metres of a power line and 258 lived between 200 and 600 metres away. The statistics suggested that living in close proximity to a power line might be linked in some way to five cases of leukaemia a year.

But Gerald Draper, leader of the study team from the Oxford childhood cancer research group, said the research had not found any scientifically valid causal link.

Earlier research showed that high-voltage lines could give out a weak magnetic field extending for about 60 metres. This was equivalent to about 1% of the earth's existing magnetic field. It could not explain why the risk of leukaemia was as great for a child living nearly 200 metres from a line as for one living directly beneath one.

Dr Draper said: "It may not be the effect of power lines at all. It may be something to do with the kind of areas where power lines are located, or the sort of people who live in these areas."

About 4% of people in England and Wales live within 600 metres of a high-voltage line.

John Swanson, a scientific adviser to National Grid Transco and one of the authors of the report, said: "We have strengthened the evidence that something is happening, but we haven't made any connection about why it is happening: if only we had."

Dr Swanson added that he would not let proximity to power lines deter him from a property. But if all things were equal and another property was available further away, he would find that preferable.

Another major research programme, the UK Childhood Cancer Study, suggested in April that most cases of childhood leukaemia had their origins before birth and might be triggered by infections early in life. It said there was minimal risk from electrical installations or magnetic field levels. Children in daycare before the age of one were less likely to develop leukaemia, perhaps because exposure to minor infections might prime the immune system, it suggested.

John Toy, Cancer Research UK's medical director, said people living near power lines had no need to panic. "The triggers that cause childhood leukaemia are most likely a random course of events over which a parent has no control," Professor Toy said.

But Eddie O'Gorman, chairman of the charity Children with Leukaemia, said: "There is now a clear case for immediate government action. Planning controls must be introduced to stop houses and schools being built close to high-voltage overhead power lines."

A Department of Health spokeswoman said: "At this stage, research has not proved that power lines cause leukaemia in children."

However, the department had already set up a group of experts to consider whether there was any need "to develop precautionary measures to reduce exposures to electromagnetic fields".